Technical Field
The present invention relates to a field of radiation detection, and more specifically to an X-ray scanning method and system.
Description of Related Information
X-ray scanning and imaging techniques have been commonly utilized in various industries such as security inspection, industrial radiography, medical examination, etc. Specifically, X-ray security inspection equipment has been widely used in various places such as stations, ports, airports, convention centers, etc. In most X-ray scanning systems, the scanning process is performed in such a way that a plane of emitted X-ray beams remains stationary and a delivery system moves an object to be inspected through the plane of emitted X-ray beams. However, in some situations, the object to be inspected is unsuitable for being moved. For example, the object to be inspected may be a fixed industrial device; or in a human-body inspection, it is not easy for a person to keep balance when he/she moves. In this case, in order to perform the scanning process, the scanning system has to move the plane of emitted X-ray beams. Therefore, there is a need for an imaging system in which, when an object to be inspected remains stationary, an X-ray scanning apparatus can move a plane of emitted X-ray beams such that a scanning process may be performed.
When an object to be inspected remains stationary and a plane of emitted X-ray beams is moved, since inevitable vibration occurs during motion of certain components, an X-ray generator cannot remain at rest relative to a detector during the scanning process. This may lead to an unstable intensity of X-rays received by the detector. In this case, if traditional correction approaches are employed to process an acquired image (comprising for example simple data transmission, noise reduction processing and analysis, as commonly used), stripe noise will inevitably occur in the image, as shown in FIG. 1.
Overview
Aspects of the present innovations provide X-ray scanning methods and systems to solve the noise issue in the prior art, which is caused by mechanical vibration in existing X-ray scanning process for static object.
To solve the above problems, the present innovations may provide an X-ray scanning method, comprising:                collecting background data when no X-ray is emitted;        collecting air data when X-rays are emitted and there is no object to be scanned in an inspection channel;        scanning an object to collect original scanning data; and        preprocessing the original scanning data according to the background data and the air data to acquire scanned image data.        
In some implementations, the step of collecting the background data may further comprise averaging the background data to acquire averaged background data.
According to certain implementations, the step of collecting the air data may further comprise averaging the air data to acquire averaged air data.
In various implementations, the step of preprocessing the original scanning data according to the background data and the air data to acquire scanned image data may further comprise:                segmenting a scanning region into an object region containing therein the object and an air region without the object according to the original scanning data; and        searching the air data for particular air data closest to a value of original scanning data for the air region, and performing a gain correction for the original scanning data according to the background data and the closest air data to acquire the scanned image data.        
In further implementations, the step of segmenting the scanning region into the object region containing therein the object and the air region without the object according to the original scanning data may comprise segmenting the scanning region into the object region containing therein the object and the air region without the object by using a predefined threshold.
In other implementations, the step of segmenting the scanning region into the object region containing therein the object and the air region without the object according to the original scanning data may also comprise segmenting the scanning region into the object region containing therein the object and the air region without the object by using a thresholding method, an edge detection method, or a region growing method.
In still other implementations, the step of preprocessing the original scanning data according to the background data and the air data to acquire scanned image data may further comprise:                defining a sub-region of the scanning region in which no object is allowed to be placed as the air region, and defining the rest of the scanning region as the object region; and        searching the air data for particular air data closest to a value of original scanning data for the air region, and performing a gain correction for the original scanning data according to the background data and the closest air data to acquire the scanned image data.        
According to other aspects, the present innovations may also provide an X-ray scanning system, comprising:                an X-ray generator, adapted for emitting X-rays;        a detector that remains stationary relative to the X-ray generator, adapted for collecting detecting signals of the X-rays; and        a processor coupled to the detector, adapted for processing the detecting signals of the X-rays that are collected by the detector, wherein the processing may comprise:                    employing the detecting signals collected by the detector when the X-ray generator emits no X-ray as background data;            employing the detecting signals collected by the detector when the X-ray generator emits the X-rays and there is no object to be scanned in an inspection channel as air data;            employing the detecting signals collected by the detector when the X-ray generator emits the X-rays to scan an object as original scanning data; and            preprocessing the original scanning data according to the background data and the air data to acquire scanned image data.                        
In various implementations herein, the processor may further be adapted for:                averaging the background data to acquire averaged background data; and/or        averaging the air data to acquire averaged air data.        
According to certain implementations, illustrative systems may further comprise a collimator, which is fixed in an optical path between the X-ray generator and the detector, wherein the collimator remains stationary relative to both the X-ray generator and the detector, adapted for collimating the X-rays emitted by the X-ray generator.
In some implementations, the processor may further be adapted for:                segmenting a scanning region into an object region containing therein the object and an air region without the object according to the original scanning data; and        searching the air data for particular air data closest to a value of original scanning data for the air region, and performing a gain correction for the original scanning data according to the background data and the closest air data to acquire the scanned image data.        
According to certain implementations, the processor may be further adapted for segmenting the scanning region into the object region containing therein the object and the air region without the object by using a predefined threshold.
In other implementations, the processor may be further adapted for segmenting the scanning region into the object region containing therein the object and the air region without the object by using a thresholding method, an edge detection method, or a region growing method.
In still other implementations, the processor is further adapted for:                defining a sub-region of the scanning region in which no object is allowed to be placed as the air region, and defining the rest of the scanning region as the object region; and        searching the air data for particular air data closest to a value of original scanning data for the air region, and performing a gain correction for the original scanning data according to the background data and the closest air data to acquire the scanned image data.        
As such, when performing an X-ray scanning for a static object, the X-ray scanning method and scanning system according to the embodiments of the present innovations may measure the background data and the air data and process the scanning data, thereby solving the noise problem caused by the mechanical vibration and thus improving the measurement accuracy.